The embodiments described herein relate generally to a phase change memory device and a method for manufacturing the same, and more particularly, to a phase change memory device having heater electrodes and a method for manufacturing the same.
A phase change memory device is a memory device in which information is stored using a difference in electrical conductivity or resistance between a crystalline phase and an amorphous phase of a phase change material. In the phase change memory device, memory cells are configured such that they are electrically connected to switching elements, etc. formed on a semiconductor substrate, to implement addressing and read/write driving operations. In the phase change memory information is stored using a difference in conductivity owing to the phase change of a memory layer, therefore data is actually stored in the memory layer including phase change regions.
In a phase change memory cell current flowing through a switching element and the like electrically increases the temperature of a phase change region. The variation in temperature of the phase change regions reversibly converts the structure of a phase change material between the crystalline phase and the amorphous phase to store information. The stored information is read through measuring the resistance of the phase change material by directing a low current to the phase change region.
Currently, in the phase change memory device, reduction in power consumption and reduction in operation current are being explored. In order to achieve reduction in power consumption and reduction in operation current in the phase change memory device, it is necessary increase the level of integration, decrease contact resistance, and increase heat dissipation in the phase change memory device. The level of integration of the phase change memory device may be increased by reducing the area of a switching element for transmitting current to a phase change layer. The contact resistance in the phase change memory device may be reduced by sufficiently securing the contact area between a heater electrode for directly heating the phase change layer and the switching element. Heat dissipation in the phase change memory device may be increased by increasing the resistance of the heater electrode and reducing the contact area between the heater electrode and the phase change layer.
Recently, the area of the switching element has been reduced to some extent and the resistance of the heater electrode has been increased to some extent because the switching element of a phase change memory device is implemented using a PN diode occupying a small area and a heater electrode is made of titanium nitride (TiN) or silicon germanium (SiGe) having great specific resistance.
However, the contact area between the switching element and the heater electrode and the contact area between the heater electrode and the phase change layer are in a trade-off relationship with respect to each other, such that it is difficult to simultaneously reduce the operation current and reduce the power consumption in the phase change memory device.